In its normal operation, the left ventricle of the heart pumps oxygen-rich blood to arteries in the vasculature of the body through the aorta. As the heart pumps, the aortic valve, which is located between the ventricle and the aorta, opens and closes to control the direction of blood flow. Specifically, during a heartbeat, the valve is open to allow blood to flow from the ventricle into the aorta. Between heartbeats, however, the aortic valve closes to form a tight seal that prevents blood from leaking back into the ventricle. For any of several reasons (e.g. aging, or birth defects), it can happen that the aortic valve is somehow damaged and may become stenosed. When this happens, the aortic valve does not open to its normal extent and the flow of blood from the heart into the aorta is constricted. This leads to a heart condition that is commonly known as aortic valve stenosis (AS).
In a patient with AS, the aortic valve is stenosed and the heart is forced to pump blood through a narrowed opening through the aortic valve. Over time, this narrowing causes pressure to build up in the left ventricle of the heart. In order to compensate for this pressure overload, the muscles of the left ventricle enlarge (hypertrophy) so that the heart can pump with more force. It eventually happens, however, that the stenosis in the aortic valve increases to the point the heart can no longer maintain adequate blood flow through the stenosis. At this point, the patient experiences several characteristic symptoms of AS. In general, this occurs when the aortic valve, when open, has a valve opening area that is approximately one square centimeter (1 cm2).
Heretofore, the treatment for AS has been accomplished either surgically by doing a valve replacement, or by performing a percutaneous balloon valvuloplasty. In the case of a valve replacement, an extensive surgical procedure is required wherein the aortic valve is replaced either by a mechanical or a porcine valve. On the other hand, being a percutaneous procedure, balloon valvuloplasty is somewhat less involved than a valve replacement procedure. Nevertheless, for many reasons including a high recurrence rate, and despite its initial acceptance, balloon valvuloplasty is now used infrequently and only palliatively or as a bridge to surgery.
In light of the above it is an object of the present invention to provide a percutaneous device and method for treating aortic valve stenosis that effectively makes controlled shallow incisions in the leaflets, of the aortic valve to thereby establish a more normal flow of blood from the left ventricle of the heart into the aorta. Another object of the present invention is to provide a cutting device that can be safely advanced through the vasculature of a patient, and subsequently withdrawn therefrom, while permitting surgical incisions at selected locations in the vasculature. Still another object of the present invention is to provide a cutting device and method for treating aortic valve stenosis that is simple to manufacture, easy to use, and comparatively cost effective.